If me, I'd have them flush the OATs coolant on their dime because they left that pressurized cap loose
FYI if you don't know it...OATs (organic acid tech) does NOT play well with O2 in the system and they why the overflow bottle is now pressurized. That is to keep O2 out while checking coolant level. To check these days of OATs & HOATs, just look through the translucent overflow bottle body & the graduations molded into it
The risk is that enough O2 was ingested into the coolant system to do its nasty work with the acid & acid etched metal (oxide) that turns into acidic, gelatinous globules that then stick to the cool-down surfaces of the radiator. That then rots the tube metal
FYI for what it's worth...
