I don't consider 70F to be too low... they would grow stronger/better if it was higher but we all have to deal with what IS and sometimes, we can't really control the temperature. For example, on a current grow I've got going, the day time temps are about 74F - but when those lights go off, the temps drop to the upper 50s which concerns me greatly as she's still vegging... The only thing I'm able to do that I'm COMFORTABLE with is to only give her 2 hours of dark a day rather than 4 or even 6... The bigger concern, imho, is the humidity and that's going in the right direction - down! I'll take slower growth over bud rot every day and twice on Sundays..
Relax, everything will be fine... and btw, EVERY grow could be better... you'll never reach perfection so don't stress out trying to achieve it!
Good luck....