1st. congratulate to you for making money, especially if you bought a call option @79 expiry in Dec, your % gain would have been excellent compare to shorting the shares.
2nd. though channel seems to be working majority of the time, violation can happen like this case. Hence there is always a risk. In this case you just miss the 90-85 difference of profit. What happen if you shorted @85 and you would have been in lose
3rd. As long as you got your profit from the upswing in channel. You will need to exercise your DISCIPLINE to take your profit, not lamenting further miss of opportunity. As opportunities abound.
Always ask yourself how much loses can you bear before you cut loss and do your homework to verify so to account for your own trading decision :-)