Yes, that looks like the knit wasn't as solid as it could be to begin with. Cheddar types can be tricky to get to knit properly if the curds get cold, especially early on. I recommend Sailor's method of "pressing in the pot" for cheddar. Basically, put your put in a sink of warm water, put your mould in the pot, and press while the curds are in the pot. The general idea is that the water keeps the pot warm, which in turn keeps the air in the pot warm, and that, finally, keeps the curds warm. Being warm helps them to knit better. I make a fair number of cheddar types, and I just press by stacking weights on top of the follower. I'm generally pressing for 10 - 30 minutes, take the cheese out, remove the cloth, flip it, redress, and back in the mould and increase the weight for another 10-30 minutes, and repeat. A number of redress and flips early on also seems to help (as the curds also have retained heat from during the make - remember, the cheddaring process should be done keeping the curds at temperature! Also, the curds look like they could have been milled a bit smaller, say break each of those chunks in half or thirds next time. I usually press around 1 PSI and eventually work up to about 2.5 PSI and I usually get really good knits (because I just stack weights I can usually cover the pot with a towel as well, which helps keep heat in. If you have a press that gives you more pressure, you should have no problem.