My 8 month old sleeps for 2 hours in the morning and 2 hours at night and then from 7pm - 5am. And he is miserable without naps.
If he was happy I wouldn't put him down (I'm actually looking forward to when he doesn't need so much sleep, having 2 other children I want my 'freedom' back).
If he's happy, not whingy or grumpy and sleeping well at night and eating well, etc - he's fine
Half your luck