A wee bit snug--argh!! I had checked my gauge, but I forgot about intarsia and how colour-work sometimes makes me tighten my gauge **sigh**
Thankfully all is not lost. I had planned to make the same hat for my nephew (in fact, my plan is to make a couple of girl versions too using pink or purple instead of grey). My next challenge will be to cast on for a second skull hat, but this time I'll use bigger needles (instead of 5.0mm, I'll use 6.0mm). Hopefully that adjustment will be enough to create a larger hat to fit my son's melon, LOL.