I always hear good things about the Leatherique products though I have no experience using them yet.

Thanks both of you for your advice

Those are not creases those are cracks, and if you don't start to take care of your seats it'll turn into tears/rips. Leather at the end of day is just skin and it needs to be taken care of and cleaned otherwise its dry up and crack. The other side driver seats always goes first as it recieves the most wear and tear every time you slide in and out of your car. Keep your seat clean by using a good leather cleaner and then apply a good leather conditioner, that way it will keep the leather clean moist and supple and last much longer.

Well to best of my knowledge, I guess this how leather age's as all my cars had leather seats and I have witnessed this throughout from Japanese - Germans - US car brands.  Only thing for DIY is to keep polishing with meguir leather conditioner once a month, will help reducing the further occurrence as if leather is properly moisturized then these creases will not increase and slight chance it may reduce after regular use.

Hi, my rx 350 is exactly one year old now. The driver seat  bottom has developed random crease lines on the outer side edge though no cracks, yet looks very ugly and worn.  Any help how to restore  Will try posting a picture. 

Just to add to this, coolant is not the only important thing, always check the hoses that connect the radiator, the radiator itself and the condenser which is most cases is just under the radiator, top up the AC gas just to be sure. I do not want to advertise any oe company here, but most major service centers and car showrooms offer a free AC check up and discounted parts just before the start of summer. Take advantage of these special packages and you will save yourself from facing issues in mid summer heat.