I'm no ECG guru but my understanding is that left axis deviation occurs if there is a conduction deficit in part of the hearts electrical conduction system called the left bundle branch.
The books reckon' theres no problem indicated unless the QRS complex (the big spikey bits) are also significantly negative as well.
In short, if the boffins say you've nothing to worry about then you've nothing to worry about.
In fact...if you ever find yourself at a cardioligists ball with an ECG monitor handy then you have a pretty nifty party trick!