My 5 month old kitten, Ripley, starts panting after about 10 minutes of playing roughhouse with my 3 month old kitten Cali. Ripley has to rest for about 10 minutes before she plays again. Cali can play rough house for hours and not get winded. When we see Ripley pant, we put her by her water so she could drink but she doesn't take a drink. Should I be concerned that Ripley does not have the same stamina as Cali?