warmer air AFTER recharging AC

Yes, you need to evacuate the system and then recharge with proper amount. I have found that depending on where leak it located, air can be introduced into system. With your can gauge you are only reading low side pressure. More than likely, with your added refrigerant, you now have too much hi side pressure. This will not cause an icing condition, just will increase outlet air temp. With every increase in hi side pressure, is a corresponding increase in operating temp, and that equals higher outlet temp.