Sorry just seeing this now.
Yeah for blue numbers. Not to rain on the parade but that is one heck of a drop for 2 hours post shot and suggests Mittens might be having an active cycle tonight. I'm guessing that Mittens is outside hunting down a mouse or 2 but if you can get her in, it would be a really good idea to test her again tonight. That drop suggests she may be going even lower than blue and you really need to know just how low she's going on that dose to keep her safe. If you can get her in and want to let her back out, I'd suggest giving her some high carb food to slow down the drop in BG. ProZinc usually reaches peak action (lowest point in cycle) sometime between +4 and +7 post shot. If you can't get her in, at the very least, leave some high carb food out for her to get if she needs it.
I know Mittens isn't happy being kept indoors, but anytime you see a drop of more than 50 points in 2 hours, it would be much safer to keep her in, test again in an hour or so and feed her accordingly. You can let her back out once you know her BG is not dropping any more. You don't want her having a hypo episode while outside at night.