If they are good tenants, and you want to keep them, and 7% is a lot of money (7% of $500 is $35; 7% of $2500 is $175), and they are amenable to the increase but want a month delay (I suspect the extra month is to give them time to move, but I digress), then you have something else to consider. 

I suspect you did something closer to the 2nd than the 1st.  

(we're currently doing a full rehab, including basement drop with underpinning, in PG county--our first such project--and I suspect it's going to be a very long process) I'd be interested in learning more about your work as we decide how best to move forward with our DC project.

The $380/Month HOA affects the desired rent to value ratio, but I suspect at market rent you have a pretty good rental for potential cash flow (good rent to value ratio).Your $600 a month in new loan payments must be including tax and/or insurance because those loan terms equate to ~$440 by my calculations.As others have stated your rate on the new loan seems too high. 

To keep  safe if we suspect an infestation, what we do is to keep a bottle of 90% alcohol in the car.

I suspect a local real estate group can suggest someone for you.

When finance calculators came out, some used wrong formulas and they were very close but not correct and they had to be tested against a known calculator to ensure we got the same information.Granted, there is no really accurate gyration to go through to estimate rehabs, I suspect after doing 25 jobs or so, many will leave the gadgets behind as they will be close enough from just walking through, knowing where they'll be.Not trying to kill the fun, just saying people need to learn what's behind the curtain. :)

I suspect that this will increase over the next few years, as so little new product has been built since 2007, and that pent up demand will support spec building in more and more areas.

I was suspecting that she was not walking the dog, as the apartment began to smell like the dog was going in the apartment.

I have spoken with my rep there on numerous times and have visited the offices once as well and have never found anything suspect in my dealings with them.