ToysRLuv, Oh, dropping a nap is horrible isn't it? Some babies do take a long time to adjust to only one nap.
I see what you mean about treating bedtime as the second nap. I think lots of babies do this.
On the positive side, even if being awake in the middle of the night is something which happens a bit more, I reckon it'll stop once he gets used to having just the one nap.
At the moment DS is getting up at 6.30 and he's napping for 30-35 mins at 10, and then at 3pm (I wake him after 45 mins but he wants to sleep for 2 hours!). If I don't wake him for the second one he won't go to sleep till 9.30pm or later; if I wake him I can have him asleep by 7.30pm. But it seems to be changing almost weekly after months of a short nap at 9am and a long one at 1pm.
The advice in the No-Cry Nap Solution is to keep two naps for as long as you can, but they still end up with insufficient sleep no matter what you do! 
(Apologies, OP, for the slight hijack. :))