I suppose you got a lower body fat %, so your muscles are more visible too. But, indeed, when eating more calories than one burns, one certainly gets muscles much faster, and by eating in a clean way (no sugar, hardly any saturated fat, for me 20-20-60% energy from fat, proteins and carbs), fat stays away. I've been bulking on 125% of my energy need for months now, haven't seen an increase of fat percentage ... UNTIL Christmas came, now no trousers fit anymore because of the fat on my stomach
After Christmas, my waist size stayed exactly the same, at least that tells me nothing is wrong with my bulking diet. I'm going to a cutting diet at 80% for 2 or 3 weeks or so to get back to my 'pre Christmas stomach' and continue bulking ...
Re priming your body for muscle growth .. Have a look at Torbjorn Akerfeldt's ABCDE-diet, you should be able to find that in Google. It's about cutting and bulking for about 2 weeks and changing all the time. Don't take his advise of cutting and bulking so strongly .. I got in touch with him a few months ago and he said his research pointed toward cutting at about 90% and bulking at about 125% for women. I tried for a month or so, but got too tired with changing my diet all the time, but for people who don't think this is a big problem, I would suggest you give it a try.