I made a yeast starter last night with 1500 ml of water, 150 g DME and a Wyeast 1056 smack pack. After boiling, total volume was just under 1500 ml. I put it in a 2 liter erlenmeyer flask on a stir plate and covered the top with foil. By morning it went Mt. Vesuvius and had bubbled out the top all over my stir plate. I've definitely lost some yeast.
I've made several of these before and never had this happen. Is this unusual? What is a reasonable volume starter for a 2 liter flask? Should I chill, decant, and do another starter to make up for the lost yeast or just pitch it and see what happens? It's for an IPA with an OG of 1065, so I don't want to underpitch.