I'm a larger and older and male (so I should have a lower HRM), and my 5k HR at similar pace is very similar, so the rate doesn't seem out of line. The pace isn't far off your 5k either, eh, which suggests it should like 95% of HRM? Unless you have been doing a lot of long slow distance and have a step change in aerobic capacity.
Some might say 5k ish pace 400m intervals don't need much recovery/HR drop between.
Grain of salt, of course, since I haven't run in a month. :-)
It shouldn't be 95% when I'm just running a quarter with rest in between, I would think... maybe toward the end of entire 5K. I'm really basing those comments on how I was feeling. Last time I did this workout, I felt more recovered between the intervals, and the HR seemed to confirm that.