While I can't say for sure in your case, I can tell you with confidence that many new mowers (small engines) do, in fact, have an electrical fuel shutoff just as you describe. My bet is that your machine does have one.
Good luck with the leak - find it before your mower burns to the ground
-Tony

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1992 500SEL 25K
1995 E320 40K
1995 SL600 120K
2002 JX8 Sport 43K
2005 Volvo S40 95K
2006 Isuzu NPR 304K (Frankencamper)
2007 Crown Victoria 150K
2014 Smart Electric 20K