That's not bad and as long as it stays around where it is, it's still OK.
Temps could be improved with different/better cooling and that will give you an extra cushion between running too hot and having safe temps. 55c is the standard norm most state as being the limit so there is room for improvement but as is, it's not a big deal as long as temps under load don't go any higher the what you have now. As for TIM/paste, reapplying it sometimes helps and will make a difference.
Yes, cheapo paste/TIM will cause problems, always go with good TIM whenever possible.