Do "Giraffe Weevil" males build Nests
As the comment by @terdon says, the most likely explanation is that your species identification is mistaken. The superfamily Curculionoidea, which contains the weevils (Curculionidae are the true weevils) is also extremely species rich. Without seeing a picture of what you found, there are many other similar species with long necks in the family Attelabidae, which is the family of Trachelophorus giraffa. For instance, the wikipedia page includes a picture Apoderus longicollis which is very similar to the Giraffe weevil from Madagaskar, and it is supposed to be found in India (see GBIF info):

 

Paracycnotrachelus is another genus found in Asia where some species have long necks. Another giraffe-necked species is also found in New-Zealand - see Lasiorynchus barbicornis - so the overall body shape is not that unique (note that much of the elongation in this species is of the snout though):



Even if we should never rule out the possibility of range changes/introductions, this must be based on close examinations of the specimen, and it is even more unlikely in this case since Trachelophorus giraffa seems to be a very specialized species.