While it is a published "legal" connection, and should be fine, the slightest delay could make you miss your flight to AMS.
Flight 1408 continues on to BOS from MSP, and flights to/from BOS are supposed to arrive and depart from the high C gates in PHL, so you'll most likely arrive somewhere in the vicinity of C18-C20. Terminal A east is a bit closer from there, but if you're leaving out of the high A gates, it's decently far.
I'd say that from Terminal C to Terminal A is a good 3-5 minute jog. I'm 6'5" tall, so my strides are pretty long - YMMV.
If I were you, I'd try to move up to an earlier flight to PHL to be safe.