Why is Warning chime sounding.

Hi, ref audi a5 2009. The warning chime or gong
recently started to sound whilst driving every so
often but there is no visible warning message.
When i start engine i get a chime telling me service
is due which im sorting out soon but that only rings
the once. This has happened out of the blue and
for no apparent reason with as i say no visible
message. Could it be connected to the over due
service or may it be something to do with the
media centre. The service chime has popped up in
last few weeks but until now it only went off once
upon starting but now the chime sounds randomly
but cannot see a message indicating what it may
be. Any help wud be helpful thanks.