Too good to be true credit card decision?

[IdealFugacity]

i have two credit cards, never paid anything less than the full statement, auto-debited online:

1) No-rewards chase card, got just before college started. regular increases have resulted in a credit limit of $4900.
2) Chase PerfectCard. 3% on gas (up to $500 worth of gas, for $15 cap), 1% on everything else (no cap). 6 months old, just got the credit limit increased yesterday from $2000 to $2500.

Call up Chase a few minutes ago, punch in the info for Card number 1, and speak to a rep:
"hi, I've had this card for about 6 years now, and have consistently made payments. i was wondering if i could change it into a Rewards card, and not lose my credit history?"

"sure, just let me know what rewards card you want"


I am planning on going with the same card; Chase Perfectcard. that way i'll have a total of about $7500 limit with the same rewards.

Anyone think this is too risky, in terms of losing my credit history?