could it be valve seals...at 49k???????????

[Vicb]

Just bought a MINT 90 Scottsdale with 48K, all records, even the original factory sticker. Was owned by eldery gentleman who passed away recently. It had immaculate care and looks new....3k oil changes. I've just noticed a quick puff of blue smoke on startup each morning...no more smoke the rest of the day..it runs great...could an engine (its a 350) with mileage this low possibly need valve seals???..Previous owner said it uses about 1/2 qt of oil between 3 k changes...Is it ok to continue to run it if valve seals are needed, or should I have it done???? any ideas on cost???? Truck is perfect otherwise.....