Possible, yes. Likely, no. Assuming you didn't make any significant changes to your training regimen and/or diet, it's most likely you simply lost some bodyfat.
You didn't describe your body composition, but at certain BF levels (in males, ~12-20% or so), loss of BF is notorious for having a negative effect on perceived body composition. That is, when men are in this BF% range, losing fat often makes them feel smaller, because there's no appreciable improvement in their definition.