I had a similar problem with my 200, parked in the same spot outside the house for 6 or so months then one day, NOTHING from any of the keys, went into the house checked the forum and interferance seemed to be the main explanation. I openned the car with the key and with the alarm blaring set off to work. 10 seconds later alarm stops and I carry onto work. Once at work get I got out of the car and locked it as normal, locked and unlocked it several times without problem.
Got home at night and it wouldn't lock, jumped in the car drove into the next street and hey presto it locked !!! Went back home NOTHING. Totally frustrated I just walked around the car trying and trying, then when I was stood next to the fuel filler cap click it locked. Pushing my luck click it unlocked but only if stood at the filler cap. Locked it and went in the house thinking right first thing tomorrow it's back to Lexus.
Next morning went out it openned without a problem and touch wood the problem has'nt happened since,it was a totally mad 2 days.
Summery : I think it wikll just pass and interferance is probably to blame.
Good Luck