Maybe the leak is facing that way and reverberating in a way that makes it sound like its on the drivers side? If you replaced both air bags then the leak is in a line somewhere or at the compressor. If this is the case, its odd that it didn't leak for several days but then started up again. Maybe something was done wrong with the replacement bags? I've never messed with this air suspension before so hopefully someone who knows more will chime in.

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2007 E70 X5 4.8i Sport Package
8x,xxx Miles
"My Precious" (Smeagol voice)