Sounds like the beginning of gyno to me, I would keep on the lookout for them getting any puffier. Make sure they aren't sore and that there aren't any hard lumps appearing under your nips... Are you taking any anti-estrogens?
YUM
When ever I use Test and D-Bol my nips always get water retention underneath them which appers to be fat, it always goes away after I stop the use of them. Make sure you watch for other signs of gyno ie.....itchy, sore nips