3 handed vs heads up - shouldn't it be about the same ?

[Bubu]

Hi,

I started playing a guy 3 handed and then we fell down to heads up for a while (online UB 10-20 hold' em). I thought I had a handle on his game 3 handed, but he surprised me by really pumping up his aggression level when we lost the third player. I don't think he was changing gears. He has done this twice now - 3 handed relatively tight. 2 handed loose super aggressive (capping the flop, re-raise semibluffing the turn). Anyone seen this effect before ?

Am I missing out on something ? Should the difference between 3 handed and heads up really change your game that much ?

cheers,

Bubu