If you are noticing arm tiredness/strain during rides and it bothers you, that's a pretty good indicator that something isn't quite right. Could be saddle fore/aft, could be (too much) bar drop, and (oddly) could be either too much or too short a reach to the bars. Could be something of all three.

You might want to have someone take a look at your fit, or (re)set it yourself using something like P. White's guide.