get it checked at a breastfeeding clinic asap, and don't be fobbed off. i don't know where you are but there's a great consultant at southampton.
we didn't get referred until dd was 7 weeks old and feeding had been awful for all that time. snipping the tongue tie took seconds but it was too late for us - breastfeeding never recovered as we had been told to top up with formula when she had gained no weight by 4 weeks old <sigh>.
we were told that hers was quite severe (no heart shaped tongue but you could clearly see it - I was just totally unaware that it could cause problems). we were also told that if we had left it, it could have affected speech, she wouldn't have been able to lick an ice cream and she would have limited ability to perform oral sex