This is my first batch so I'm wondering if I am worrying over nothing or if I need to take action. I brewed an all extract IPA kit from Williams Brewing. I feel I was very careful with sanitation and pitched a liquid yeast pack just below 80 degrees. I used an ice bath and was able to get the wort to that temp in just shy of an hour. I am using a bucket and it appears that all the seals are good. I did start the yeast packet and let it swell, but I did not have time to brew until close to three days after the pack was fully swollen. I am getting very tiny bubbles in my airlock, but nothing that appears to really be moving and definitely not "vigorous" fermentation. Do I need to pitch more yeast or should I wait it out?
I don't think you have anything to worry about yet.
If you can see inside your bucket or carboy (without opening) you can see if the krausen has formed yet, and how thick it is. The krausen looks like this:
When it starts, it will just be a faint ring, then the entire surface is covered, and then it gets thicker.
Only when krausen has formed is fermentation really underway at it's most vigorous.
The quantities liquid yeast provided by the major manufacturers results in a slight underpitching, so there can be some lag time there. Also, 64F is on the cooler side, so things will proceed at a more moderate pace. (You'll also get cleaner tasting beer.) With all that considered, 36 hours is still quite early.
Just wait it out - I'm sure you'll see it pick up in a day or so.
Given the fact that your yeast packet was activated and then left for 3 days, it's likely the yeast just went dormant again after consuming the nutrients in the packet (which caused all that swelling), which would account for a lag time in fermentation.
Wyeast's FAQs address a similar possible issue - pitching a yeast packet without activating it. Their answer is that the yeast is still perfectly viable, but to expect a possible lag time in fermentation.
As others have said, just be patient and have faith.
Welcome new brewer, you have asked every first time brewers favorite question. I would say just relax, you probably did nothing wrong, airlock bubbles are not a good sign of fermentation. But worrying during your first brew is part of the experience. If you don't have a hydrometer yet get one and measure the gravity is about a week. Google a bit for your brew's expected Final Gravity reading and see if you are coming close.